Method of and apparatus for providing compressed air for the operation of wash boxes



y 1932- A. J. SAYERS 1,865,726

METHOD OF AND APPARATUS FOR PROVIDING COMPRESSED AIR FOR THE OPERATION OF WASH BOXES Filed Nov. 24, 1930 2 Sheets-Sheet 1 July 5, 1932. A. J. SAYERS- ,7

METHOD OF AND APPARATUS FOR PROVIDING COMPRESSED AIR FOR THE OPERATION OF WASH BOXES Filed Nov. 24, 1930 2 Sheets-Sheet 2 Patented July 5, 1932 MET' ATEN'E ,ALBERT J. SAYERS, OF CHICAGO, ILLINOIS, ASSIGNOR TO LINK-BELT COMPANY, OF

CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS METHOD or AND APPARATUS FOR PROVIDING COMPRESSED Ana FOR THE ornrmrron or WA$H noxns Application filed November 24, 1930. Serial No. 497,773.

My invention relates to improvements in wash boxes and especially to method of and apparatus for providing. compressed air for operation of the box and controlling its operation. Among the objects of the invention are to provide a new and improved air supply means and control system thereforwhereby the operation of the box may be.

started and stopped'suddenly without wasteful loss of power, whereby the operation of the box may be directly controlled and adjusted to take care of varying conditions, and whereby. the operation of the box may be con: trolled and rendered more accurate, economical and efficient. v

My invention relates primarily to Bash jig systems or jigs of the Baumes typewhere a continuous bed of material to be washed is fed along fixed screen and wherein water is fed upwardly through the screen in a series of pulsations, the water being forced upwardly through the screen by compressed air which is admitted to and released from an air pocket in communication with the working or material containing portion of the jig.

It has in the past been customary to supply this compressed air by means of a positive displacement blower which compresses air at ajsubstantially constant pressure and constant rate but which supplies a pulsating column of air. When it is desired with a posi tive blower to stop jig operation, itis customary to exhaust the compressed air into the atmosphere so as. to keep it from going to thejig. The compressor goes right on using power to compress this air so that the power requirement is equally great whether the jig is working or not as long as the compressor is in operation. Moreover owing to the pulsating character of the air column fed by the compressor it is necessary to have a large receiver of capacity great enough to insure that the pulsating effect would be lost in the receiver and not felt at th'e jig as otherwise the pulsating effect of the compressor will interfere with. the pulsations controlled by the quick acting valve whichalternately admits air to the jig box and permits its escape therefrom.

I propose to obviate the difiiculties inherent in the positive displacement .blower operated by using a centrifugal compressor whlch dlscharges compressed air at a pressure which is generally constant lrrespective of the volume of air taken and I propose to controlthe output of this compressor and the air input into the jig by a blast gate in the intake side of the centrifugal compressor. When thisblast gate is shut the compressor works in a vacuum, delivers no air and the only power required is the power to overcome mechanical friction. As this gate is opened, an increasing amount of air is drawn in and the only power required is the power necessary to compress the volume of air admitted to the intake side. This makes it possible to control with a high degree of accuracy the amount of air fed to the jig and since the blast gate is easily manipulated, sudden changes in condition may be taken care of without diiiiculty, for instance, if coal stops coming the blast gate is shut, the jig stops and the bed is maintained ready to start working as soon as coal supply is resumed. The compressor continues to operate at its rated speed without discharging air. Another advantage of myarrangement is that since the compressor delivers air in a continuous flow without pulsation, no receiver is needed.

My invention is illustrated more or less diagrammatically in the accompanying drawings, wherein Figure liis a top view;

Figure 2 is a front elevation:

FigureB is a section along the line 3+3 of Figure 2;

Figure 4 is a perspective of the compressor intake pipe showing the blast gate.

Like parts are indicated by like charac ters throughout the specification and drawlngs.

A is a box having a curved bottom A and supported on a framework A It is divided into two longitudinal sections by a longitudinal partition A which extends down into the body of the box below the surface of the water maintained therein and working areas. The box is also divided upfuse elevator boots.

into a series of separate air compartments A A and A A by transverse partition walls A, A which extend upwardly on the air side of the box as far as the heads A which close each of the air compartments and on the jigging side extend up to the screens A A which are set at difierent levels, the screen A which is at slightly higher level than the screen A being on the upstream end of the box. Raw material, for instance, coal is fed into the box through 'the sluice A and treated coal is discharged in a washed and treated condition through the sluice A.

B is a screw conveyor located in a trough at the bottom of the jig box A and is adapted to discharge refuse material, which passes through the'screens and drops down into the body of the water, into the refuse elevator boots B B located at either end of the box. B B are refuse gates at the intake and discharge ends of the screen, adapted to be controlled by hand wheels B B at the front of the machine. Refuse gravitates to the bottom of the bed of flowing coal upon the screen and particles too large to pass through the screen pass out between these gates and the screen through the chutes B B and are discharged thereby into the re lVhen coal is being treated, this refuse is dirt, clay, slate, shale, bone coal, and the like, which is heavier than the coal from which it is separated by gravity. It will be understood that the water '5 level in the jig box is maintained high enough above the screens so that the entire bed of material as it travels along them is sub merged. I

Associated with each one of the air pockets is a quick acting valve C, comprising a reciprocating piston member driven by a stem C and connecting rod C from an eccentric C on the valve operating shaft C. Air is supplied to each of these valves from a header C through a pipe C controlled by a manually adjusted valve C, there being one quick acting valve and one manually adjusted valve for each air pocket. The quick acting valve at it reciprocates, alternately causes compressed air to be supplied to the air pocket and to be discharged therefrom to the atmosphere. Vhen air passes in through the valve C from the pipe C to the air pocket, it forces the water down on the air side of the longitudinal dividing walls A and this water rushes up through the screen and through the bed of material onthe screen tending to stratify it. When the valve C permits the air to escape from the pocket, the water tends to return by gravity in a reverse direction through the bed of material and the screen. This return tends to resist or at least delay stratification and to prevent this, water is supplied to the ig box under pressure through the pipe C of the controlled by the manually adjusted valve C". This water being under pressure head rushes in to replace the water forced by the air through the screen and bed of material and thus there results a constant pulsating flow of water upwardly through the stratified bed, the water having passed through the bed, overflows from the discharge end The rate at which the valve shaft rotates controls the rate of pulsation of the water in the jig box and since as will hereinafter appear the air controlled by the quick acting valve comes to it at a generally constant pressure without pulsation, the only element controlling pulsation is the quick acting valve.

D is a centrifugal blower driven by a motor D and discharging directly into the header C. This blower furnishes air under pressure to the header at approximately constant pressure independent of volume displaced up to the maximum capacity of the blower and since the blower installed in the device is of course of big enough capacity to carry the maximum load which may be imposed upon it, it is a fact that in the main pressure variations are reduced to a minimum so far as the blower itself is concerned. The blower D draws in air through the intake pipe D This pipe is controlled by a blast gate D preferably of the butterfly type. This gate is controlled by an operating rod D extending across the machine to the front where it is provided with a handle or lever D whereby the operator may adjust it.

Since a centrifugal compressor giving generally constant air pressure independent of variations in the amount of air displaced is used, since this centrifugal compressor discharges air in a constant non-pulsating flow, no large receiver is needed as would be the case if a blower giving pulsating air current were used and so the quick acting valves are the only elements in the system controlling the rate of pulsation and since they release successive impulses of air at substantially constant pressure the rate of pulsation and its magnitude may be accurately controlled.

The hand control valve between the header and each air chamber will be adjusted by the operator when the machine first starts to control the flow of air from the header to the quick acting valve because experience shows that sometimes different quantities of lzgir should be fed to the different air chamers.

The blast gate in the intake to the compressor has a two-fold function. It is used to altogether stop the supply of compressed aid to the system when the operator desires so to do and it is used to control the amount of air fed to the system while in operation.

This first function, namely as means to altogether cut off air supply is important it sometimes happens in mine or coal plant operation that the supply of coal to the jig box may be temporarily discontinued. When this is the case, it is desirable to stop operation instantly so as tov preserve the bed on the screens. If operation stops gradually, the coal having ceased to flow, the bed will be gradually dissipated, unsatisfactory washing will meanwhile take place and as operation gradually startsup later, it takes some time for the bed to settle downto, a position of equilibrium and during that time also unsatisfactory washing will take place. Moreover, during thetime that operation maybe starting the box, if the supply of coal is resumed suddenly, it maybe flooded with coal, this also tending toward-inaccurate and unsatisfactory separation.

The other purpose of the blast gate is to adjust the supply of airto the workingconditions. A designer knowing approximately what the conditions are, .what kindof coal, the capacity, and the elevation'above sea level, can select his various sizes and dimensions with some degreeof accuracy but it always happens that he cannotpredict with absolute accuracy allof the variables which enter into the situation so when the machine is set up and v put into operation,

the operator manipulates the blast. gate until he finds that adjustment which-gives most satisfactory operation and he uses this adjustment. However, barometric conditions may change, the quantity of coal which it is desired to treat may change or the character of the coal may change. Any of these changes may result in a different air requirement. The operator can manipulate the blast gate to comply with such varying requirements. r

This use of the blast gate controlling the intake both forstopping and starting the operation of thebox and for adjusting it for proper operation is exceedingly valuable also in that it saves power. If a positive displacev ment compressor is used, every time the shaft turns over a fixed amount of airis displaced and if this compressor is runby an electric motor as is usually. the case, and if this electric motor. is a constant speed motor as is highly desirable. thenv variation in the amount of air-fed to the jig box must be as is usually the case accomplished byproviding in the. system an atmosphere valve, which valve is opened or closed or adjusted to permit a controlled amount ofair to be blown .out of the system. It costs just as much to compress this air and blow it out of the system as it does to compress it and blow it through the box and if it is desired to stop operation altogether fora time as above referred to, when this valvehas to be opened wide theentireoutput of the com pressor is wasted. This. must be done because to accomplish immediate starting the compressor must be running at full speed this is avoided by the arrangement which I have described because by throttling the intake, I am enabled to control the amount of air discharged by the compressor and the powerused to operate the compressor, be-

cause the power required is very closelyrelated to the air output. If the blast gate is closed entirely and no air is displaced, then the compressor rotates freely in a vacuum and the motor has to provide power only to overcome mechanical friction. As the gate is opened more and more air is displaced and the motor provides only enough power to displace that amount of air desired. I claim: v I 1. A wash box comprising a tank adapted to contain water, a longitudinal partition therein, a screen located beneath the surface of the water on one side of the partition, a closed air pocket, the undersideof which is bounded by the surface of the water onthe opposed side of the partition, means for maintaining a continuous flowing bed of fragmentary material on thescreen beneath the water level, a centrifugal air compressor,

a pipe connectingit and the air pocket whereby 5:

it may supply air under pressure to the pocket and a quick acting valve associated with the pipe and the pocket and adapted alternately to permit the inflow of compressed air from the pipe to the pocket and the outflow of compressed air from the pocket to the atmosphere and ablast gate in the air intake of the centris fugal compressor adapted to adjustably control the amount of air discharged by the compressor, the capacity of the pipe connecting the air pocket and the air compressor being substantially equal to the capacity of thecom pressor itself whereby the storage of air be: tween the compressor and the jig chamber is prevented. r v

2. A wash box comprising a tankadapted to contain water, a longitudinal partition therein, a screen located beneath the surface of the water on one side of the partition, a closed air pocket, the underside of which is bounded by the surface of the water on the opposed side of the partition, means for maintaining a continuous flowing bed'of fragg mentary material on the screen beneath the water level,-an air compressor, a pipe connecting it and the air pocket whereby it may supply air under pressure to the pocket and a quick acting valve associated with the pipeand the pocket and adapted alternately to permit the inflow of compressed air from the I... pipe to the pocket and the outflow of com pressed air from the pocket to the atmosphere and means for adjustably controlling th'e amount of air compressed by and supplied to.

the air pocket by the compressor, thecapacity.

of the pipe Connecting the air pocket and the air compressor being substantially equal to the capacity of the compressor itself whereby the storage of air between the compressor and the jig chamber is prevented.

3. A wash box comprising atank adapted to contain water, a longitudinal partition there in, a screen located beneath the surface of the water on one side of the partition, a closed air pocket, the underside of which is bounded by the surface of the water on the opposed side of the partition, means for maintaining a continuous flowing bed of fragmentary material on the screen beneath the water level, an air compressor, a pipe connecting it and the air pocket whereby it may supply air under pressure to the pocket and a quick acting valve associated with the pipe and the pocket and adapted alternately to permit the inflow of compressed air from the pipe to the pocket and the outflow of compressed air from the pocket to the atmosphere, and means for adjustably controlling the amount of air supplied to the air compressor and compressed by it, the capacity of the pipe connecting the air pocket and the air compressor being substantially equal to the capacity of the compressor itself whereby the storage of air between the compressor and the jig chamber is prevented.

4. A wash box comprising atank adapted to contain water, a longitudinal partition therein, a screen located beneath the surface of the water on one side of the partition, a plurality of closed air pockets, the undersides of which are bounded by the surface of the water on the opposed side of the partition, means for maintainingv a continuous flowing bed of fragmentary material on the screen beneath the water level, a centrifugal air compressor, a header adapted to receive compressed air directly from the compressor, separate pipes connecting the header with each air pocket whereby the compressor may supply air to each pocket, a quick acting valve associated the centrifugal compressor adapted to adjustably control the amount of air discharged by the compressor, the capacity of the pipe connecting the air pocketand the air compressor being substantially equal to the capacity of the compressor itself whereby the storage of air between the compressorand the jig chamber is prevented.

5. A wash boX comprising av tank adapted to contain water, a longitudinal partition therein, a screen located beneath the surface of the water on one side of the partition, a plurality of closed air pockets, the undersides of which are bounded by the surface of the water on the opposed side of the partition,

means for maintaining a continuous flowing bed of fragmentary material on the screen beenath the water level, an air compressor, a header adapted to receive compressed air directly from the compressor, separate pipes connecting the header with each air pocket whereby the compressor may supply air to each pocket, a quick acting valve associated with each pipe and pocket and adapted alternately to permit the inflow of compressed air from the pipe to the pocket and the outflow of compressed air from the pocket to the atmosphere, and means for adjustably controlling the amount of air compressed by and supplied to the air pockets by the compressor, the capacity of the pipe connecting the air pocket and the air compressor being substantially equal to the capacity of the compressor itself. whereby the storage of air between the compressor and the jig chamber is prevented.

6. A wash box comprising a tank adapted to contain water, a longitudinal partition therein, a screen located beneath the surface of the water on one side of the partition, a plurality of closed air pockets, the undersides of which are bounded by the surface of the water on the opposed side of the partition, means for maintaining a continuous flowing bed of fragmentary material on the screen beneath the water level, an air compressor, a header adapted to receive compressed air directly from the compressor, separate pipes connecting the header with each air pocket whereby the compressor may supply air to each pocket, a quick acting valve associated with each pipe and pocket and adapted alternately to permit the inflow of compressed air from the pipe to the pocket and the outflow of compressed air from the pocket to the atmosphere, and means adjustably controlling the amount of air supplied to the air compressor and compressed by it, the capacity of the pipe connecting the air pocket and the air compressor being substantially equal to the capacity of the compressor itself whereby the storage of air between the compressor and the jig chamber is prevented.

7. A wash box comprising a tank adapted to contain water, a longitudinal partition therein, a screen located beneath the surface of the water on one side of the partition, a closed air pocket, the underside of which is bounded by the surface of the water on the opposed side of the partition, means for maintaining a continuous flowing bed of fragmentary material on the screen beneath the water level, a centrifugal air compressor, a pipe connecting it and the air pocket whereby it may supply air under pressure to the pocket and a quick acting valve associated with the pipe and the pocket and adapted alternately to permit the inflow of compressed air from the pipe to the pocket and the outflow of compressed air from the pocket to the atmosphere, a manually adjusted air controlled valve in the pipe between the compressor and the quick acting Valve, and a blast gate in the air intake of the centrifugal compressor adapted to adjustably control the amount of air discharged by the compressor, the capacity of the pipe connecting the air pocket and the air compressor being substantially equal to the capacity of the compressor itself whereby the storage of air between the compressor and the jig chamber is prevented.

8. A wash box comprising a tank adapted to contain water, a longitudinal partition therein, a screen located beneath the surface of the water on one side of the partition, a plurality of closed air pockets, the undersides of which are bounded by the surface of the water on the opposed side of the partition, means for maintaining a continuous flowing bed of fragmentary material on the screen beneath the water level, a centrifugal air compressor, aheader adapted to receive compressed air directly from the compressor, separate pipes connecting the header with each air pocket whereby the compressor may supply air to each pocket, a quick acting valve associated with each pipe and pocket and adapted alternately to permit the inflow of compressed air from the pipe to the pocket and the outflow of compressed air from the pocket to the atmosphere a manually adjusted air controlled valve in each pipe between the headerand the quick acting valve, and a blast gate in the air intake of the centrifugal compressor adapted to adjustably control the amount of air discharged by the compressor, the capacity of the pipe connecting the air pocket and the air compressor being substantially equal to the capacity of the compressor itself whereby the storage of air between the compressor and the jig chamber is prevented.

9. The process of controlling the operation of a jig comprising a plurality of air pulsated wash boxes which consists in separately and independently adjusting the input of air to each wash box once and for all and in thereafter simultaneously and separately adjusting the supply of uncompressed air to the system to control the operation of the entire jig in consonance with variations in the work done by it, the compressed air being directly delivered to each wash box without storage of compressed air between its source and the wash box.

10. The process of controlling the operation of a jig comprising a separating zone through which a continuous bed of material to be separated travels wherein such bed of material is supported in a pulsating mass of water made up of a plurality of separate pulsating zones which consists in separately and independently adjusting the air input to each of said zones to controlthe relation between the various zones once and for all during operation and in thereafter simultaneously and separately adjusting the supply of compressed air to all of said zones to control the pulsations of the jig in consonance with the work done by it the compressed air being directly delivered to each wash box without storage of compressed air between its source and the wash box.

11. The rocess of controlling the operation of ajig comprising a separating zone through which a continuous bed of material to be separated travels wherein such bed of material is supported in a pulsating mass of water made up of a plurality of separate pulsating zones which consists in separately and independently adjusting the air input to each of said zones to control the relation between the various zones once and for all during operation and in thereafter simultaneously and separately adjusting the supply of compressed air to all of said zones to control the pulsations of the jig in consonance with the work done by it, the air control being applied to the air before it is compressed for feeding into the system, the compressed air being directly delivered to each wash box without storage of compressed air between its source and the wash box.

Signed at Chicago, county of Cook and State of Illinois this 19th day of Nov. 1930.

ALBERT J. SAYERS. 

